Flavor and aroma are important characteristics of smoking articles. To improve the flavor and aroma in smoking articles, flavorful and aromatic substances, including various natural extracts, have been included in smoking articles. For example, various processes for producing and using tobacco extracts, aroma oils and concentrates are proposed in the U.S. Pat. No. 3,136,321 to Davis; U.S. Pat. No. 3,316,919 to Green; U.S. Pat. No. 3,424,171 to Rooker; U.S. Pat. No. 4,421,126 to Gellatly and U.S. Pat. No. 4,506,682 to Mueller and European Patent Publication No. 338,831 to Clapp et al.
U.S. Pat. No. 5,413,122 discloses making a flavorful and aromatic composition from .beta.-hydroxy .alpha.-amino acids by contacting the amino acids with a liquid having an aqueous character. The ratio of liquid to amino acid is 4:1 to 40:1. The mixture is subjected to heat treatment in an enclosed environment to react the amino acids and to thereby provide an aqueous solution of volatile pyrazine flavorants. The resulting aqueous extract containing flavorful pyrazines is then applied to smoking materials to provide flavor and aroma in the smoking articles.
It has also been proposed to react sugars with amino acids to produce desirable flavorants for smoking articles and foods. For example, U.S. Pat. No. 3,478,015 discloses heating a mixture of an amino acid and a sugar in the presence of a polyhydric alcohol and using the reaction product as a flavoring material.
U.S. Pat. No. 3,920,026 describes reacting the amino acid valine with a sugar, other hydroxycarbonyl compound, or dicarbonyl compound under heat treatment in a solvent such as glycerol or propylene glycol and at a temperature of about 100.degree. C. to about 200.degree. C. for about 0.5 to 5 hours. Optionally, a catalyst such as a flavanoid or hydroxyacid is included in the reaction. The reaction products can be used as flavorants in tobacco compositions.
U.S. Pat. No. 4,306,577 discloses the production of flavorants for smoking compositions by reacting reducing sugars and selected amino acids in the presence of ammonium hydroxide and optionally in the presence of an aldehyde in an essentially solvent-free system at a temperature range of 90.degree. C. to 115.degree. C. The selected amino acids are those that have at least two nitrogens such as glutamine, asparagine, lysine, and arginine.
Similarly, U.S. Pat. No. Re. 32,095 discloses reacting a reducing sugar with a source of ammonia in the presence of a trace amount of certain amino acids at a temperature in the range of about 90.degree. C. to about 115.degree. C. for about 5 to 15 minutes. The trace amino acids include aspartic acid, glutamic acid, asparagine, and glutamine. The weight ratio of sugar to amino acid is in the range of 200-300:1, and the weight ratio of sugar to ammonia source is about 5-15:1.
Although these and other materials can enhance the taste of tobacco products, because of the volatile nature of flavorant and aroma materials, they are often lost at least in part during cigarette manufacturing and packaging steps. Also quantities of the flavorant and aroma materials can diminish during the storage of the finished smoking articles and it is often necessary to increase the initial content of flavorants to compensate.